It is known in the art that the typical method of packaging the hub in the front upright with the constant velocity “CV” joint in the case of independently suspended wheels presents a compromised steering geometry in front-wheel-drive “FWD” and all-wheel-drive vehicles, which is especially pronounced in the case of light trucks and Sport Utility Vehicles. Three key parameters are essential to achieving an ideal FWD steering geometry, the first being low kingpin inclination angle for minimizing camber loss as steer lock is added, the second being negative scrub radius in order to minimize drive torque and brake reaction induced steering force variations, and the third parameter being short hub length owing to the fact that the wheel center, the dished disc, may not protrude outboard of the tire side wall, so as to prevent any damage to the hub which could otherwise be incurred in the course of normal use. To wit, a negative scrub radius exists when the kingpin intersects the ground level outboard of the wheel rim's center plane.
According to current practice for independent suspension layouts in general, the wheel bearing of choice for driven wheels—whether steered or not—is either the double row angular contact ball bearing, or a double row tapered roller bearing, or a pair of opposed angular contact ball bearings. Within the scope of independent type suspension layouts, accepted wheel hub packaging practice does not make it feasible to achieve negative scrub radius with low kingpin angle, especially not on SUVs and light trucks, as any currently practiced approach to wheel bearing packaging solutions force the wheel end—or outboard—CV joint undesirably far inboard of the wheel rim's center plane.
Another undesirable byproduct of current state of the art CV joint packaging practice is that said CV joint's said outer race proper is cantilevered by virtue of the bearing, or bearings, being substantially positioned on the integral stub axle, which stub axle axially extends in a generally lateral outwardly direction from said CV joint's said outer race proper. With regards to steering geometry, it is a given that the kingpin must simultaneously pass through the centers of both outboard suspension joints and the CV joint. Consequently, according to the known state of the art, if near-zero or negative scrub radius is desired, that can only be achieved at the expense of desirable kingpin axis inclination, and vice versa. The subject of kingpin inclination put aside, state of the art solutions to near-zero or negative scrub radius lead to other fundamentally negative side effects.
To name but two, these are a definite lack of wheel bearing robustness for a given hub package size, and a lack of provision for periodic wheel bearing preload adjustment in the course of routine maintenance. A further undesirable side effect is that the planes defining the inboard and outboard rows of rolling elements are very closely coupled to one another, and as wear develops over the bearing's life span, it magnifies the road wheel's free play in directions being oblique to the rotational-plane.
It follows then that there is a need for a relatively short hub supported by robust wheel bearings, which two characteristics of course are mutually exclusive with state-of-the-art solutions, so long as the CV joint's outer race proper at the wheel end of the drive shaft is not being integrated to the inboard wheel bearing.